This invention relates to an electrical contact material and a method of preparing the same. More particularly, it relates to a contact material in which a metallic oxide produced by means of an internal oxidation is dispersed in Ag and to a method of preparing such materials.
The metallic contact materials of the kind referred to can be effectively utilized for making contacts of such electromagnetic contact devices as relays, magnet contacts, circuit breakers and the like, by improving the materials in their anti-welding property.
1. Disclosure of Prior Art
There have been suggested various types of the contact materials for use in the electromagnetic contact devices. For these contact materials, it has been demanded that such three features as the wear resistance, anti-welding property and low contact resistance are concurrently realized to a high level, but it is considered to be extremely difficult to provide a contact material which satisfies concurrently these three features in practice. On the other hand, such contactor devices as the relays are often employed in circuits or devices for controlling any input and output, in which event an inrush current is apt to occur in the input and output circuits, and, accordingly, it has been demanded for the contact material the anti-welding property can be realized to a high level so that no welding will take place even upon occurrence of the inrush current.
As the contact material for the electromagnetic contact devices, generally, Ag-CdO materials, Ag-SnO materials have been employed. While contacts of the Ag-CdO materials have been widely employed as a good material which showing a stable low contact resistance because CdO as an oxide is caused to sublime due to arc heat upon opening and closing operations of the contacts so as not to cause any heap up of the oxide produce on the contactor surfaces, they still have not been sufficiently satisfactory in the level of the anti-welding property with respect to the inrush current. Contacts of Ag-SnO have been excellent as compared with the Ag-CdO materials in the anti-welding property, but these materials have involved a problem that the low contact resistance cannot be stably obtained.
In U.S. Pat. No. 3,880,777,Akira SHIBATA has suggested a contact material which consisting of Ag containing at least two of Zn, Sn and Sb as well as one of Group IIa elements in the Periodic Table added along with Ni or Co, in attempt to have the contact material provided with both the anti-welding property and low contact resistance, but this contact material still has been defective in the level of the both characteristics obtained.
2. Technical Field
A primary object of the present invention is, therefore, to provide a contact material of Ag-CdO system produced by means of the internal oxidation, which shows a sufficiently excellent anti-welding property, stably low contact resistance and high wear resistance, and a method of preparing such a contact material.
According to the present invention, the above object can be attained by providing a contact material in which CdO or the like metallic oxide produced by means of the internal oxidation within Ag is dispersed, wherein Mn and Al are further contained as metal elements for the metallic oxide.
Other objects and advantages of the invention shall be made clear in following description of the invention detailed with reference to working aspects thereof.